Method of producing chromophotographs on paper and chromodiapositives



1,613,515 1927' F. JANZEN METHOD OF PRODUCING CHROMOPHOTOGRAPHfi ONPAPER AND CHROMODIAPOSITIVES Filed March 14. 1923 Patented Jan. 4, 1927.

UNITED STATES PATENT OFFICE.

FRANZ JANZEN, or: BERLIN-TEMPELHOF, GERMANY, ,ASSIGNOR 'ro WILLYVOIBACH, OF BERLIN, GERMANY.

mn'rnzon or PRODUCING cnnomornoroenarns ON PAPER AND ennomonmrosr-'rrvns.

Application filed March 14, 1923, Serial No. 625,185, and in GermanyMarch 16, 1922.

This invention has reference to unicolored and multicoloredchromophotographs on paper and to diapositives, and it is particu larlyintended to so improve the manufacture thereof "that the manufacture ofthe prints is facilitated and it is also an object of my invention todevise novelv means of producing the color sensitive coating and. oftransferring the picture to the printing plate. Other objects andadvantages of my invention will appear as the specification proceeds.

,Broadly speaking my invention is based on the so-called suction orimbibing method, according to which a suitably prepared copy from thenegative is colored with aniline dyes, and is then covered with gelatinepaper so as to be in intimate contact therewith. After some time thecolor from the copy has been transferred to the paper with all thedelicate shades and tints in the lighted and shaded portions. Upon theseprinciples is based for example the so-called pinatype process owned bythe Hochet Dye-Works of Meister-Lucius & Briining. In accordance withthe process referred to an ordinary black-and-white diapositive is madefrom the negative, and from the diapositive a print is made upon a glassplate coated with gelatine which has been sensitized by means ofchromates. The printing plate thus obtained is now colored with anilinedyes which are adapted to tint unhardened gelatine very strongly, whilehardenedgelatine is only slightly tinted or not colored at all.

I The hues produced in this manner are, moreover, not only proof againstwashing, but they also fail to be blurred and to merge into thegelatineso that sharp pictures are produced. This previous methodpresents the inconvenience that it requires-a diapositive and then aprinting plate to be made therefrom. 'Nor is it possible to obtain cleanpictures, inasmuch as the pictures are always somewhat smudged withcolors, no matter how much the plates have been hardened.

Upon being used repeatedly the printing plates become gradually darker,so that it soonbecomes impossible to produce exactly registering partialpictures. Entirely new printing plates then have to be made.

"-All these drawbacks and inconveniences are overcome in my inventionwhich otherwise makes use of dyes and pigments having the sameproperties as in the previous processes referred to. In the new process,howm'er. the diapositive copied from the negative is utilized directlyas a printing plate. In View thereof a film is coated with a layer of asuitable colloid containing insoluble substances in the finest state ofdistribution scarcely colored by the dyes and pigments hereinbeforementioned, inasmuch as the colors are capable of permeating into thegelatine which has become porous, so to speak, by the addition of theinert substances. mixed colors will fail to produce the desired results.On the other hand, in contact with gelatinized paper the colors areextracted and are sharply and unobjectionably transferredto the paper.

In the accompanying drawing, which is a distorted diagrammatic section,the transparent supportis indicated at 1, the bichromated colloidcoating at 2, and the insoluble granules which are distributedthroughout said coating at 3.

The foils produced are rendered sensitive by the addition ofbichromates, and are copied from the back sides. They are then developedlike a igment picture in warm water without being transferred, and arethen tinted. Such development in warm water effects the washing out ofthe finely divided substances, since the microscopical substance doesnot dissolve in the colloidal layer, nor are they finely embeddedtherein and their washing out from the colloidal layer leaves the latterin a porous condition as above stated. Inasmuchas the unexposed portionsare washed 0 t in accordance with the degree of hardening, they alwaysremain clear and clean. The printing foils obtained do not become darkereven upon being re- It has been ascertained .that unpeatedly used, sothat exact registration of the partial pictures in thethree-color-printing process is ensured.

As far as I am aware inert or indiiferent substances, such as asphaltum,mineral coal have been added to gelatine only for the purpose ofproducing in pigment pictures a certain kind of grained back groundsimilar to the so-called helio-engraving.

The invention has been described herein only in its broad aspects, andit is obvious that it may be modified to suit existing conditions andthe convenience of the operator, and without being restricted to anyparticular form of execution, except as set forth in the claims hereuntoappended.

I claim 1. The method of producing photographic pictures in naturalcolors, consisting in producing printing film's by copying from the backsurface of negatives exposed through three color filtersred-bluegreen;the )rinting films each consisting of a colloidal iayer applied to atransparent base and thoroughly impregnated with extremely finelydivided substances insoluble in the colloidal layer, washing out suchsubstances to render the film porous, saturating said porous film with adifferent color solutlon, and successively pressing such color saturatedfilms upon photographic paper which has been rendered durable againstlight to transfer the colors to the paper.

2. The method of producing photographic pictures in natural colorsconsisting in pro-.

ducing printing films by copying from the back surface ofnegativesexposed through three color filtersredbluegreen; the printing filmsconsisting of a colloidal layer applied to a transparent base andthoroughly impregnated with extremely finely divided substances, such aschalk, soot of volatile signature.

FRANZ J ANZEN.

